Mechanisms of falls in mountain biking

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How do humans avoid falls and injuries when negotiating risky environments? Falls are the leading cause of injuries across the lifespan, and a leading cause of death among those under age 36. Among healthy young adults, most cases occur while pursuing sports and outdoor recreation. The long-term vision of my research is to improve our understanding of the mechanisms of injuries in healthy humans. Our efforts have focused on falls in seniors, and head impacts in hockey, and have combined laboratory experiments with real-life data (from video and sensors) to reveal new insights on the cause and prevention of these events. Building on these efforts, the proposed research program examines the mechanisms of falls and injuries in off-road bicycling (or mountain biking, MTB). We focus on MTB as a microcosm for examining how human decision-making and reactive responses (feedforward and feedback mechanisms) govern balance, falls and injuries when negotiating complex and hazardous environments, and for determining how the mechanisms of falls depend on sex, gender, and age. Our first objective is to identify and compare the causes and circumstances of falls and injuries in different populations of MTB riders. We will conduct a prospective observational cohort study to determine how the frequency and characteristics of falls and injuries in MTB depends on sex, gender, age, experience, riding skills, fear-of-falling, and use of protective gear. Our results will provide the first evidence on how falls occur in MTB to inform prevention strategies. Our second objective is to identify how riders respond to falls in MTB through attempts to recover balance and avoid head impact. We will leverage publicly available videos of falls to classify protective responses (including stepping, upper limb bracing and rolling) and environmental and situational factors. We will extract time-varying kinematics and use models to analyze the strength and speed requirements for protecting the head during falls. Our third objective is to examine the factors that determine path selection and speed in MTB. Through field measures with video and wearable sensors, we will examine the roles of sex, gender, age, experience, riding skills, and fear-of-falling. In complementary laboratory experiments, we will use eye tracking to examine how visual information is used in path selection and obstacle negotiation. We will also use customizable features (e.g., ramps of different width and height) to determine how riders select paths based on estimates of the risk for falling, and the risk for injury from a fall. By studying MTB as an experimental model that stresses the postural control system, we will reveal new insights on the mechanisms of falls and injuries that will be important to biomechanics and motor control researchers, and relevant beyond the MTB community for informing injury prevention through skills development, safe habits, technology, and environmental design.